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Chemical compound From Wikipedia, the free encyclopedia
15-Crown-5 is a crown ether with the formula (C2H4O)5. It is a cyclic pentamer of ethylene oxide that forms complex with various cations, including sodium (Na+)[2] and potassium (K+);[3] however, it is complementary to Na+ and thus has a higher selectivity for Na+ ions.
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| Names | |
|---|---|
| Preferred IUPAC name
1,4,7,10,13-Pentaoxacyclopentadecane[1] | |
| Identifiers | |
3D model (JSmol) |
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| 1618144 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.046.694 |
| EC Number |
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| 3897 | |
| MeSH | 15-Crown-5 |
PubChem CID |
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| RTECS number |
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CompTox Dashboard (EPA) |
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| Properties | |
| C10H20O5 | |
| Molar mass | 220.265 g·mol−1 |
| Appearance | Clear, colorless liquid |
| Density | 1.113 g cm−3 (at 20 °C) |
| Boiling point | 93–96 °C (199–205 °F; 366–369 K) at 0.05 mmHg |
| log P | -0.639 |
Refractive index (nD) |
1.465 |
| Thermochemistry | |
Std enthalpy of formation (ΔfH⦵298) |
-881.1--877.1 kJ mol−1 |
Std enthalpy of combustion (ΔcH⦵298) |
-5.9157--5.9129 MJ mol−1 |
| Hazards | |
| GHS labelling: | |
 | |
| Warning | |
| H302, H315, H319 | |
| P305+P351+P338 | |
| NFPA 704 (fire diamond) | |
| Flash point | 113 °C (235 °F; 386 K) |
| Safety data sheet (SDS) | msds.chem.ox.ac.uk |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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15-Crown-5 can be synthesized using a modified Williamson ether synthesis:[4]
It also forms from the cyclic oligomerization of ethylene oxide in the presence of gaseous boron trifluoride.[5]
Analogous to 18-crown-6, 15-crown-5 binds to sodium ions. Thus, when treated with this complexing agent, sodium salts often become soluble in organic solvents.
First-row transition metal dications fit snugly inside the cavity of 15-crown-5. They are too small to be included in 18-crown-6. The binding of transition metal cations results in multiple hydrogen-bonded interactions from both equatorial and axial aqua ligands, such that highly crystalline solid-state supramolecular polymers can be isolated. Metal salts isolated in this form include Co(ClO4)2, Ni(ClO4)2, Cu(ClO4)2, and Zn(ClO4)2. Seven coordinate species are most common for transition metal complexes of 15-crown-5, with the crown ether occupying the equatorial plane, along with 2 axial aqua ligands.[6]
15-crown-5 has also been used to isolate salts of oxonium ions. For example, from a solution of tetrachloroauric acid, the oxonium ion [H7O3]+ has been isolated as the salt [(H7O3)(15-crown-5)2][AuCl4]. Neutron diffraction studies revealed a sandwich structure, which shows a chain of water with remarkably long O-H bond (1.12 Å) in the acidic proton, but with a very short OH•••O distance (1.32 Å).[6]
(15-crown-5))+.jpg)
A derivative of 15-crown-5, benzo-15-crown-5, has been used to produce anionic complexes of carbido ligands as their [K(benzo-15-crown-5)2]+ salts:[6]
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